There are 209 children in a canteen.
38 of the girls and
47 of the boys wear caps, there are 121 children in the canteen who do not wear caps. How many boys do not wear caps?
| |
Girls |
Boys |
Total |
| Do not wear caps |
5 u |
3 p |
121 |
| Wear caps |
3 u |
4 p |
88 |
| Total |
8 u |
7 p |
209 |
Number of children who wear caps
= 209 - 121
= 88
5 u + 3 p = 121 --- (1)
3 u + 4 p = 88 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 363 --- (3)
(2)
x 5 15 u + 20 p = 440 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 440 - 363
20 p - 9 p = 77
11 p = 77
1 p = 77 ÷ 11 = 7
Number of boys who do not wear caps
= 3 p
= 3 x 7
= 21
Answer(s): 21
